1. Field of the Invention
The present invention relates to a robot system having a central control unit for managing the entire operation of the robot system and a plurality of peripheral control modules for controlling the operations of the respective portions of the robot. More particularly, the present invention relates to a communication control method of transmitting operation information among program modules of the central control unit, among control modules, and between the program modules and the control modules; and an apparatus for realizing the method.
b 2. Description of the Related Art
Generally, along with widening in application range, both the mechanism and control systems of industrial robots have become complicated. Regarding the control system, it is divided into peripheral control modules for controlling the respective portions of the mechanism and signal processing and a central control unit for managing and controlling the entire operation.
Conventional industrial robots operate in accordance with a permanent work program. The peripheral equipment such as a sensor belongs to the robot controller and performs input/output of a simple signal in response to a communication instruction incorporated in the robot language.
In the conventional robot system, no serious problems occur when the robot performs a comparatively simple operation. However, when the robot system is a so-called multifunction system, it has a plurality of peripheral control modules for independently controlling the respective portions of the robot. It also includes in the central control unit a plurality of program modules, which can concurrently be performed to exchange instruction signals between any two of the control modules and the program modules. In such a multifunction system, the following problems arise.
Each peripheral control module and each program module of the central control unit must have a work program that can cope with any possible situation. As a result, when the operation of the robot system is changed, or when the operation sequence of each control module is changed, a new work program must be created.
Since the respective portions of the robot are controlled using instructions having simple contents, it is difficult for the robot to have a complicated function.
When a certain operation is instructed to a robot section and completion of the instructed operation is awaited, the central control unit and each program module must monitor a signal transmitted from the corresponding robot section in a program manner, and other program processes cannot be performed during this monitoring.
Furthermore, when each program processing module of the central control unit independently and parallelly processes the program, it cannot control a corresponding control module immediately based on the processing result if other processing modules use the communication line.